Can I manually focus when autofocus is switched on?

fermoycailin

Hi there,
Can anyone help please? I have a Nikon camera (DLSR - D3000) and most of the time have my focus switched to AF (autofocus), however as the distance from the camera to the subject varies from photo to photo, I usually focus the lens with my hands, manually, and then will autofocus the rest of the way.

Is this doing the camera any harm?

All feedback welcome - thanks!

Paulw

It depends on the lens. Many allow you to manually focus and override the autofocus motor, while some have a problem with it and you can end up busting the lens motor.

If you list the lenses, maybe some other Nikon users can comment about the specific lenses.

zerohamster

If your lens has "full time manual" then it will not harm the lens however if it does not you will be putting stress on the gears which will have to turn the motor which will eventually cause gear teeth to break or bend the gear from too much torque.
I believe most Nikon lenses will have M/A on one side of the AF switch and then M at the other position, if so then you wont be causing damage.

By general standards, if the focus ring resists your rotation or more force is used than if the M mode on the lens then the lens is not designed for full time manual operation

Most lenses that allow you to manual focus while on auto, have a seperate focus ring on them near the ring for focal length. Generally speaking, if there's not one there, you shouldn't do it yourself.

On the 50mm 1.8 Canon lens, if its on Auto and i turn the front of the lens myself, i can hear the mechanism inside it moving. On manual focus, it is silent. So by moving it while its on auto, there are chances of me damaging the focus mechanism.

fermoycailin

Hi,
The lense I have is 'Nikon DX' 'AF-S NIKKOR 18-55mm 1:3.5-5.6G'
Does this make sense to you?

If so, does it help in knowing whether I can manually focus with the switch to AF instead of M.

Also, do you know what VR is? There is also an On-Off button for this.

Thanks all.

5uspect

VR is vibration reduction. It stabilises the lens against hand shake at low shutter speeds.

Your lens doesn't appear to have full time manual focus as it's basically just the Nikon kit lens. I don't think however you will do any damage manually focusing in AF mode when you are not actually engaging the AF motor. Obviously don't resist the motor when you do engage it!

zerohamster

As 5uspect said above VR stands for vibration reduction and is Nikon's name for IS (image stabilisation).

However you will damage the lens focusing with the lens in autofocus mode regardless of whether the motor is running or not. It would break/burn out the motor quite quickly if you forced the focus when the motor was on but it would definitely damage the gears by forcing the lens' focus ring when in AF mode. The gears are only plastic and having that much torque applied to them would strip them in a small space of time so I would strongly advise against doing it for the sake of flipping a switch to use maual focus mode.

5uspect

I dunno, I've been doing it with my 50 f/1.8 for years.

EDIT: tho a quick google tells me I've been naughty.

zerohamster

Id say you have been quite lucky to not have caused damage to the lens, there is also the factor of different lenses having more/less resistance in the gear mech which would make a difference in the force on each gear,
also different motor rotation:focus ring rotation ratios would make a difference in the risk of damage.

Either way I would recommend against doing it as a general rule as you will be shortening the life of the gearbox, it's just a matter of how much you will be shortening it which depends on the torque that is applied to the gears when forced.

Is it the Canon 50mm f/1.8 or Nikon?
I know the canon one could be used as such without much risk as it has a very simple gear setup but I haven't used a Nikon 50m f/1.8.

5uspect

It's a Canon, I'm not too worried about stripping the gears TBH, there doesn't seem to be enough resistance to cause any significant stress.

zerohamster

Yeah for the canon 50mm f/1.8 you can do it without much risk of damage, it's so light that the gear ration is very small which means that there will be very little resistance to turning it. It would wear out quicker but compared to other lenses it probably has the least resistance/torque needed to turn the motor out of all other lenses as it is the lightest lens on the market I believe (130g) with a very simple gear mech.

I have a Nikon 18-55 (non VR) here that feels like there is so much resistance it would break before rotating (which I dont want to put to the test). IF the VR version is similar then it would be causing damage.

fermoycailin

Thanks all - had no idea.
Will be careful!

Thanks!

Zillah

fermoycailin wrote: »

as the distance from the camera to the subject varies from photo to photo, I usually focus the lens with my hands, manually, and then will autofocus the rest of the way.

This sentence confuses the crap out of me.

pixbyjohn

Zillah wrote: »

This sentence confuses the crap out of me.

It shouldn't really. She brings the focus close to what it should be manually, then she allows the autofocus to work for the final touch.